I've been enjoying my experience with you so far. I like how circles work, and I'm growing to like your interface.
That said, I'd like to make a suggestion.
Back in the long ago, in the beforetimes, Facebook was popularized, nay, almost entirely defined by one simple interaction between members.
I am, of course, referring to the Poke.
Things have changed since then. We live in a different world. But still, I think the Google+ brand is lacking a similar catchy whimsical type of interaction. Something that people can engage in without all manner of bothersome typing or the need to dress before engaging in a hangout.
Might I suggest the Grope+ (TM)?
Imagine each user's delight when they log on and discover that they have been Groped+ by dozens of people! Imagine the how excited users would be at the potential of being Groped+ by tech-savvy celebrities like +Wil Wheaton +Felicia Day
and +John Scalzi
The Grope+ would be easy to add to the Google+ interface. What's more, a social interaction that involves no more than a simple click of a button will appeal to busy trend-setters, the socially inept, pre-verbal children, and the hopelessly illiterate. That's a big market!
After Grope+ proves itself, you could easily add additional interactions. Grunt+ would be perfect for people who long for verbal communication, but fear the specificity of actual words. Glance+ could be made available for those who are shy or particularly coquettish.
You could even expand these interactions to niche groups, allowing users to Gnusto+ or Grok+ people or posts that they're particularly fond of.
As you can see, the marketing potential is nearly infinite.
I look forward to hearing from you in order to discuss this further.